Repair to Control Board PCB of Whirlpool Oven

[narkeleptk]

There are meters called esr that do that but they are not cheap. There is this meter (shown on the video link below) on eBay for about $20 its Amazon's description states does esr.

You may find better results searching a LCR meter. Taking measurements in circuit is not usually recommended but sometimes you can get away with it.

 

[bijanelectric]

Thanks I will look into LCR meters.

 

[Harald Kapp]

Probably cheaper to replace the electrolytics preemptively:
If the are defect, you'll have to replace them anyway, the cost for the LRC meter is on top.
If they are not defect, a set of new capacitors is probably less expensive than the LRC meter (of course depends on the number of capacitors to be replaced).
You'll have to de-solder the capacitors for checking them with a meter anyway. While you're at it you can put in new ones easily.

Just my humble opinion.

 

[bijanelectric]

I received the capacitors I had ordered from eBay last night and I soldered one on the board as shown in the following picture:
https://drive.google.com/file/d/1Rhlg6PRBJs4ADW2fRKe6eP0LBb-Grm1J/view?usp=sharing

I reconnected the board to the oven. Turned the breakers on and nothing.

Before this repair the oven lights would come on when the oven door was opened but now not even those lights come on. I disconnected and reconnected the board one more time just to be sure everything was connected properly and everything was connected properly but still nothing.

I took the board out again and de-soldered the newly installed capacitor and measured its value and it was only 30nF but I had ordered 100nF.
https://drive.google.com/file/d/1iD9r0k0vvtLomM__8z-LR3a0YxxDblCA/view?usp=sharing

I disconnected the other capacitor that was next to the burned out one and measured its value and it was 100nF.
https://drive.google.com/file/d/123IzZV8zsFgzZo94EviBqykTOQC5MMrt/view?usp=sharing
https://drive.google.com/file/d/1sB6PUXFnBGakEP1orYsS8IeWL13gqfj5/view?usp=sharing

I felt a bit upset that the one the seller on eBay had sent was the incorrect capacitor. I am now trying to get the seller to send the correct ones.

My question at this point is : can this small capacitor with the wrong value cause the interior lights of the oven to not come on in addition to the black screen of the board? Whereas before when there was an open on the pcb where this new capacitor was installed the interior lights would come on. Please explain how this is possible if the answer is yes, so that I get an idea of what is going on electronically.

I did nothing else to the pcb other than re-solder the loose resistors. I will re-post the links to the resistor pictures just in case someone has not read the previous posts on this thread and don't know what I am writing about:
https://drive.google.com/file/d/1Fp5qYGVBc_oweTYk3NNb9duDml82FILq/view?usp=sharing
https://drive.google.com/file/d/1PCrMWMisN6AvhsVO-P_8fqtElmZMJpSU/view?usp=sharing
https://drive.google.com/file/d/1tLOZ4pXKVKC-iYaKxiHr5cuyup-5SYza/view?usp=sharing
https://drive.google.com/file/d/17YNvAnD8Ie2pY1wMx7PG4mpR15mg-cl5/view?usp=sharing

Please chip in with your inputs as this repair is getting a bit frustrating at this point.
Thank you.

 

[bijanelectric]

Probably cheaper to replace the electrolytics preemptively:
If the are defect, you'll have to replace them anyway, the cost for the LRC meter is on top.
If they are not defect, a set of new capacitors is probably less expensive than the LRC meter (of course depends on the number of capacitors to be replaced).
You'll have to de-solder the capacitors for checking them with a meter anyway. While you're at it you can put in new ones easily.

Just my humble opinion.

I am sensitive to soldering, in other words I can't stand the fumes even in a well ventilated environment. Therefore I have to keep the repair to a minimum. I understand that a good repair involves replacing all capacitors but due to my physical limitations I will not try to do that (unless it becomes absolutely necessary but I doubt if that would become the case).
Thank you for your input.

 

[bijanelectric]

My mistake, I had turned off 2 breakers and then when I turned them on I had made a mistake. Anyway, with the breakers turned on correctly the oven interior lights DO come on.

So now I am wondering; would the 30 nF capacitor would have worked? If they had, I would have never found out that they were not the size I had ordered. I am tempted to solder one of the 30 nF capacitors back on the board and find out if that would make the board light up. What is your opinion?

Thank you for your inputs.

 

[bijanelectric]

I did solder the 30 nF capacitor back on the board and installed it to see if the board lights up but it did not. So either the capacitor HAS TO BE the correct size or there are other issues as well.

What puzzles me is why if the burnt out capacitor is the only issue why would the board light up intermittently after months and would work for a while before stop working. This would happen when the capacitor had already burnt out (I assume). If someone has a good explanation please share.

Thank you.

 

[bijanelectric]

Probably cheaper to replace the electrolytics preemptively:
If the are defect, you'll have to replace them anyway, the cost for the LRC meter is on top.
If they are not defect, a set of new capacitors is probably less expensive than the LRC meter (of course depends on the number of capacitors to be replaced).
You'll have to de-solder the capacitors for checking them with a meter anyway. While you're at it you can put in new ones easily.

Just my humble opinion.

I do not plan to get an LRC, I just wrote I will look into it, meaning I will check to see what kind of meter they are. As for replacing all electrolytic capacitors, visually they all look good. It would be best if someone wrote how to check the board rather than gun shooting the board. That way it would be a learning experience for everyone.

 

[Martaine2005]

A lot of desoldering and soldering is necessary for checking components out of circuit.
If you are sensitive to the fumes, I suggest you employ somebody to repair it for you.
An ESR meter is part of your electronics repair kit. “Gun shooting” electrolytics is common sense when the board is out. It’s cheap and worthwhile. Capacitance meters are handy but capacitance can measure good while ESR is high, so not very accurate. Visually looking good is not accurate either. It only helps when obviously vented or leaking.
Don’t forget that members on this forum don’t have the device (DUT) and can only go by your explanation and replies you give to their suggestions.

The initial fault was intermittent and is normally the hardest to diagnose. I would suggest you double check what you have done so far for solder bridges or poor connections.

Martin

 

[73's de Edd]

Sir bijanelectric . . . . .

I did solder the 30 nF capacitor back on the board and installed it to see if the board lights up but it did not. So either the capacitor HAS TO BE the correct size or there are other issues as well.
You need to get off your " fixation " on that now removed C29 ( et twin C30) " snubber cap " (s) as being relevant to your units basic problem.
When a a diode is conducting it will create charge carriers to carry the current - this is known as "charge storage".
When the voltage reverses as part of the normal AC cycle (50/60Hz typically) the current will keep flowing through the diode in the reverse direction until the stored carriers are depleted.
When the carriers have been flushed from the diode, then the current will abruptly drop to zero and the voltage across the diode will suddenly rise. This can generate high frequencies up to tens or hundreds of Megahertz. This can interfere either with the equipment itself or radiate (or conduct via the power cable) to other equipment. The capacitor suppresses the effect of this interference. Often a capacitor will be put in parallel with each diode rather than a single capacitor across the AC input..
Any interference will usually have modulation at twice the AC input frequency and appear as a buzz in radios or audio amplifiers or could cause havoc to digital systems.
Therefore, the use of those capacitors . . . . aka . . . "snubber capacitors" . . . . across rectifier diodes is to reduce EMI / RFI.
AND . . . .they CAN also round down the peak/ dampen an incoming transient voltage spike from the power lines.
Usually there are 4, with one across each diode, in your situation they skimped down to 2 units . I see usual choices made of 0.001 ufd or 0.01ufd values, and up to 1000v ratings on direct AC line operated uses FOR THEIR VALUES.
In my seeing their choice / use of a monolithic block ceramic capacitor and permissible "creep" voltage isolation parameters, therewith, I can thereby see that this is not going to be a full AC line voltage supply, but instead, being a 12VDC'ish level supply with even a potential sub supply being derived from it also .
Thereby, only the need of a 50-100 V cap voltage rating for the two C29-30 caps..
IF I had any photo that was able to reveal C34 E-caps rating, I would then, at least, minimally know the max voltage to expect from the supply.

I have created a conversation /personal message to you but with no comeback response from you to date. I need your eyes and ohmmeter testing since those Dumb Ass Sh*ts chose to use a GREEN foil resist atop a GREEN board

Thaaaaaassit . . . .

73's de Edd . . .

It's my cat's world . . . . . I'm just around to timely open her food cans.


.

 

[bijanelectric]

Thank you for your explanation of the circuit. That is very helpful.

I took the following 2 photos of the C34 marking as per your request. The markings state 63 V 100 µF -55 +105 °C
https://drive.google.com/file/d/1OYiAIKxxURvDSyWmDH_EILVcayCbwjJi/view?usp=sharing
https://drive.google.com/file/d/1mGCMDZVi0fWt-YjmHk6I1Vl3w6MImXsa/view?usp=sharing

As per your earlier requests:

If you need any more help from me I would need. . . . .

The voltage ratings and capacitances of the two RED and BLACK squared E-cap you see marked up.
C30 off the board measured 100 nF. R20 on the board measured 10 KΩ. (I assumed it is OK to measure the resistance on the board)

An idea / measurement of the "T" designated power transformer AC voltage outputs . . . . with me already expecting . . ~ 12'ish for the power / mechanical relays onboard . Also an -80-100ish voltage for the units PANAPLEX display.
Can you explain this request in more details? Do you want me to connect the board to the oven wires, turn the main on and measure some voltages? If so what pins? Perhaps you can get "this idea" from the C34 markings and so this request is no longer needed. Please let me know.

The polarity of the installed diode bands.
As you can see I CAN confirm transformer RED foil path to term T13 feeding into my two diodes shown options of their bands . . . one anode and one cathode shared.
Confirm if my temporarily ghosted in connection foil path from T12 to PINK- GREY is correct . . .it will also be the same . . .with one anode and one cathode shared.
Across on the diodes opposite ends there will be two banded diodes feeding a +positive of an electrolytic cap and likewise, two other unbanded diode leads feeding that electrolytic caps negative - lead.
T12 is connected to:

D69 (opposite band side marking of the diode but I am not 100% sure if the black marking is the diode's band or not),
C33 (band marking side of the diode),
C39 (opposite band side marking of the diode).​

Please see the following picture that shows close up of the rectifier diodes:
https://drive.google.com/file/d/1BgTbG5EgOcYoubz0yDt2m2ErxCv62dm-/view?usp=sharing​

 

[bijanelectric]

Edd from reading your posts I think you are pointing out that likely there is an issue with the diodes that rectify the a/c coming into the board and this caused the intermittent issue with the board, and possibly the blown capacitor.
You state that the capacitors are there to suppress noise and therefore even without one capacitor burnt out the board should work but would emit excess radio frequency noise. Correct me please if I am wrong.

Based on a video I watched regarding checking rectifier bridge diodes I checked the diode pack (D33, D34, D39, D40) against each other and against T12 and T13. With the following results. One of the results, number 5 below does not match the result that was talked about in the video so I am wondering if this board is defective or if my measurement is not correct.

1. meter + on D33 cathode (where the diode band is) and meter - on T13 --> ~1.7 voltage drop
2. reverse of the 1 Over Load
3. meter - on D34 anode (opposite of diode band) and meter + on T12 --> ~1.7 voltage drop
   
4. reverse of the 3 Over Load
5. meter + on D33 anode and meter - on D40 cathode --> Over Load (according to the video I watched this should be twice the 1.7 voltage drop or about 3.4 voltage drop, the first time I tested this it showed 1 voltage drop later I tried to check it again it showed Over Load, on another check it again showed 1 voltage drop)

Thank you for your inputs.

 

[bijanelectric]

I am really sorry to ask this but I am just wondering why no one is trying to help. Does this has something to do with the site's policy? Is this perhaps because someone is afraid that something will happen and then hell breaks loose and they end up being responsible? I am just a regular guy and hereby declare that under no circumstance I will hold anyone liable or responsible for anything I do. Hopefully if that was the case it no longer is. Any help would be appreciated. I might get some diodes and capacitors and replace the ones around the burnt out capacitor and see if that works, if no one tries to help.

 

[Harald Kapp]

I am really sorry to ask this but I am just wondering why no one is trying to help.

You have @73's de Edd working on your issue. You're in good hands. But you have show some patience.

 

[Alec_t]

I am just wondering why no one is trying to help.

Members may be struggling to work out what is connected where. You have the benefit of a board in front of you. It would help if you could highlight/annotate/label relevant points in an image. You can upload images to this site to make it easier to follow the thread.

 

[bijanelectric]

Yes Edd seems very knowledgeable. I will be more patient.
As for uploading pictures I tried to upload pictures directly to the site but every time I got an error. I tried reducing their size but still did not work. So I resorted to uploading the pictures to Google Drive and posting the links in the thread. The uploaded pictures to Google Drive have permission for anyone with the link to view them. The pictures on Google Drive look better than the pictures I have seen others post on this thread in terms of clarity and being able to magnify them. So read the posts and click on the image links and you should be able to view nice and clear pictures.

 

[Martaine2005]

Also, the forum is global. While you’re typing, others are sleeping and then off to work.

Martin

 

[Harald Kapp]

I tried to upload pictures directly to the site but every time I got an error.

Image size < 300kB usually works well.

 

[bijanelectric]

I am preparing to repair the pcb of this Whirlpool Double Oven Control board. I think a good solution is to replace all the items in the yellow box in the picture below
https://drive.google.com/file/d/1fLfoaEdpz2zbsLk1dPEMG9bOA6gJ9Hjx/view?usp=sharing

or as Edd mentioned in his earlier post :

"
Build up a duplicate set of four diodes on a hand made PCB or foil perf board, so that its 4 corner leads line up withe the original
RED-BLUE-VIOLET-GREY corners . . . . . that I Have BLACK X's within.
They will then electrically connect and physically float the board either above or below the board . . . . if there is being the constraints of a plastic cover around the whole board proper.
You initially have to remove ALL carbonization residue, all the way down to the bare board,
A burr chucked in a Dremel tool does that easily . . .or the use of a #11 blade mounted in an Xacto handle, will let you laboriously scrape all of it away.
Pull off the C29 and 30 monolithic block SM ceramic caps, and replace them with conventional leaded units of 0.01 @ 50V placed on your rebuild board.

If you need any more help from me I would need. . . . ."
​

YES EDD do need more help, please, if you read this.

All the rectifying diodes (I think that is what they are) were taken off and 2 of the can type capacitors. One of the pads for the diode that connected to the blown capacitor came off and 2 of the other diode pads on the pcb are in poor condition as shown in the picture blow:
https://drive.google.com/file/d/1Chrg-OmhOH0QEhgqL_XXGhRtndE6tkOC/view?usp=sharing

How do I repair these pads or solder the components so that they are in correct electrical connection with each other (Eliminate the pads and solder the components to each other? I can see the traces on the board so I have some idea how the components are connected to each other, but if someone can confirm what I am seeing that would be great).

Another picture of the board with some of the components removed.
https://drive.google.com/file/d/1tzbto4zQNzvnV6VUBTe5Z1IGtzfhJdGw/view?usp=sharing

The big resistors were loose on the pcb, I resolder them and they are firmer but still not very strong, there is also evidence of heat build up, hence why I would like to replace them. But replacing them won't fix the looseness of the pads they sit on in the pcb, hence they also need to have modification of their pads/connections to make sure they are firmly held in place or Edd's solution of an auxiliary pcb.

I need help with identifying the parts: Diodes, Resistors, Capacitors. Also help with where and how to order the parts. I can probably order piece meal from eBay but wondering if it would be better and more economical to order all from one source. What sources would that be? Some more pictures below to help with identifying the parts:
https://drive.google.com/file/d/15nRjCkwxiH0-3Br0lgYz551PqXZV5-5T/view?usp=sharing
https://drive.google.com/file/d/1-DhsVUCdxiMBhCHCCekoLqlAw0kEcDon/view?usp=sharing
https://drive.google.com/file/d/1Aq7o9N_5MKG9ifdavvjYj07e6ZLRt83d/view?usp=sharing
https://drive.google.com/file/d/1pouZGjGFjOptTiCvOKbofwNVdxr01XEG/view?usp=sharing

Thank you for any help you can provide.

 

[bijanelectric]

Here is what I think happened to this Whirlpool Double Oven control board to make it work intermittently: the pcb board had an intermittent open at the junction of the blown capacitor and the diode for that capacitor as shown in the picture below.
https://drive.google.com/file/d/1wuHDd_RIByW6xpVxQjgjm2FnFeUCABLe/view?usp=sharing

This caused electrical on/off type of behavior inducing high voltage which blow up the capacitor. Likely all the diodes and other capacitors including the can type capacitors are functional and good, only the open at the junction of the capacitor and the diode is the main issue plus the missing/blown capacitor.

Please chip in and help out with this explanation, does it makes sense? What can you add or correct to make it be a reasonable explanation of the intermittent nature of the problem?

Thank you.